Photofragment excitation spectrum for O(¹D) from the photodissociation of jet-cooled ozone in the wavelength range 305–329 nm

The photofragment excitation (PHOFEX) spectrum for $O(1D)$ production from the photolysis of ozone under supersonic free-jet conditions was measured, scanning the photodissociation wavelength in the region of 305–329 nm and probing the $O(1D)$ atoms by vacuum ultraviolet laser induced fluorescence at 115.2 nm. The bond dissociation energy $D00(O2–O)$ was determined to be 101.53±0.25 kJ mol⁻¹ from the cut-off wavelength in the PHOFEX spectrum for the photodissociation of jet-cooled ozone $(Trot≈5 K)$ to $O(1D)+O2(a 1Δg)$⁠. The cut-off wavelength for vibrationally hot band excitation to the dissociative continuum of $O(1D)+O2(a 1Δg)$ was also observed in the PHOFEX spectrum. It was found that the active mode for the hot band excitation was the antisymmetric stretching mode ν₃ in the ground electronic state of ozone. Sharp peaks corresponding to vibrational bands in the Huggins system were also observed in the PHOFEX spectrum of the $O(1D)$ atoms produced via the spin-forbidden dissociation process, $O(1D)+O2(X 3∑g−)$⁠. The spectral widths of the vibronic bands in the Huggins system are discussed in terms of the dissociation dynamics.